HSS 2305 Lecture Notes - Lecture 5: Glomerular Basement Membrane, Ultimate Tensile Strength, Cell Membrane
13 Dec 2016
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CHP. 7
Lecture 5: Interactions Between Cells and their Environment
Overview of Extracellular Interactions
-The outer layer of the skin, Epidermis, is a type of epithelial tissue lines the space of the free
surfaces in the body; cells adhere to it and communicate with one another
-The deepest layer of the skin, Dermis, is a type of connective tissue and consists largely of
extracellular material; they have scattered cells (Fibroblasts) which make cellular matrix
proteins
-The Basement Membrane separates the epidermis from the dermis, communication with it
helps orient the cells
The Extracellular Space
-All space and any element outside of the plasma membrane
-Portions of integral proteins and membrane lipids project into the extracellular space
Glycocalyx: is formed by the carbohydrate projections along the plasma membrane, its jobs
include: mediate cell-to-cell interactions, mechanical protection to cells and bind important
regulatory factors to the cell surface
ECM: or extracellular matrix, is an organized network of molecules that provides scaffolding to
the cells and tissues it surrounds; it provides physical and biochemical signals that regulate
shape and activities of the cell
Basement Membrane: is a highly defined extracellular matrix, 50-200nm, underlies epithelial
tissue and surrounds blood vessels, provides mechanical support, serves as substratum for cell
migration, separates adjacent tissues within an organ (ex of cells that need it: in the kidneys,
epithelial cells) and is also a barrier to macromolecules (ex: keeps protein in the blood)
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-If things go wrong you could get the following auto-immune diseases:
This Basement Membrane Disease:
-Genetically inherited which affects collagen
-You get blood and protein in your urine
Goodpasture’s Sydroe:
-Anti-glomerular basement membrane
-You make antibodies against collagen
-Affects your kidneys and lungs
Components of the Extracellular Matrix
-Each protein of the matrix contains binding sites for one another and for receptors on the cell
surface
-There are 4 main types:
Collagen
• Fibrous glycoprotein (protein with a sugar attached) found only in the ECM
• Most abundant protein in the human body >25%
• Very high tensile strength
• Produced by fibroblasts, smooth muscle and epithelial cells
• 28 types of collagen fibers have been found but each is restricted to a certain location
• Must have 3 alpha helix polypeptides
• Relies on hydrogen bonding
• Proline is a prominent A.A in collagen→ eause it’s hdrolated
• Vitamin C deficiency means improper collagen formation or Scurvy
• 2 types: Fibrillar (which assemble into ridged cable-like fibers, consist of Col, I, II, III and
an example would be tendons) or Non-Fibrillar (gives a spider web appearance with
globular domains, consists of Col IV)
Collagen Types
• Type I (most abundant, found in tendons, skin, teeth, bones) Genetic
mutation→ Osteogensis Imperfecta (brittle bone)
• Type II (hyaline cartilage, 50% of cartilage portion, located in the eye) Genetic
mutation→ Dwarfism
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